Miniaturized superconducting metamaterials for radio frequencies

Abstract

We have developed a low-loss, ultrasmall radio frequency (rf) metamaterial operating at $\sim 76\text{MHz}$ . This miniaturized medium is made up of planar spiral elements with diameter as small as $\sim \lambda /658$ ($\lambda$ is the free space wavelength), fashioned from Nb thin films on quartz substrates. The transmission data are examined below and above the superconducting transition temperature of Nb for both a single spiral and a one dimensional array. The validity of the design is tested through numerical simulations and good agreement is found. We discuss how superconductors enable such a compact design in the rf with high loaded-quality factor (in excess of 5000), which is in fact difficult to realize with ordinary metals.